U.S. patent application number 14/966053 was filed with the patent office on 2016-10-13 for apparatus for obtaining biological information.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. The applicant listed for this patent is SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Seongho CHO, Kunsun EOM, Myounghoon JUNG, Yeolho LEE, Kak NAMKOONG, Eunsung PARK.
Application Number | 20160296136 14/966053 |
Document ID | / |
Family ID | 55642344 |
Filed Date | 2016-10-13 |
United States Patent
Application |
20160296136 |
Kind Code |
A1 |
JUNG; Myounghoon ; et
al. |
October 13, 2016 |
APPARATUS FOR OBTAINING BIOLOGICAL INFORMATION
Abstract
An apparatus for obtaining bio information includes: a first
electrode portion including a current electrode and a voltage
electrode arranged to contact a first body portion of a subject; a
second electrode portion including a current electrode and a
voltage electrode arranged to contact a second body portion of the
subject; and a measuring unit configured to measure a bio impedance
of the subject by applying a current to the current electrodes of
the first and second electrode portions and detecting a voltage at
the voltage electrodes of the first and second electrode portions.
In order to decrease errors of a measured bio impedance, contact
resistances of the first and second body portions of the subject
contacting the current electrode and the first and second body
portions of the subject contacting the voltage electrode are
different from each other, for at least one of the first and second
electrode portions.
Inventors: |
JUNG; Myounghoon;
(Bucheon-si, KR) ; PARK; Eunsung; (Seongnam-si,
KR) ; NAMKOONG; Kak; (Seoul, KR) ; EOM;
Kunsun; (Seoul, KR) ; LEE; Yeolho; (Anyang-si,
KR) ; CHO; Seongho; (Gwacheon-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRONICS CO., LTD. |
Suwon-si |
|
KR |
|
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
|
Family ID: |
55642344 |
Appl. No.: |
14/966053 |
Filed: |
December 11, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 5/681 20130101;
A61B 5/026 20130101; A61B 5/0537 20130101; A61B 5/6898
20130101 |
International
Class: |
A61B 5/053 20060101
A61B005/053; A61B 5/026 20060101 A61B005/026; A61B 5/00 20060101
A61B005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 8, 2015 |
KR |
10-2015-0049954 |
Claims
1. An apparatus for obtaining bio information, the apparatus
comprising: a first electrode portion comprising a current
electrode and a voltage electrode which are arranged to contact a
first body portion of a subject; a second electrode portion
comprising a current electrode and a voltage electrode which are
arranged to contact a second body portion of the subject; and a
measuring unit configured to measure a bio impedance of the subject
by applying a current to the current electrodes of the first and
second electrode portions and detecting a voltage at the voltage
electrodes of the first and second electrode portions, wherein
contact resistances of the first and second body portions of the
subject contacting the current electrode and the first and second
body portions of the subject contacting the voltage electrode are
different from each other, for at least one of the first and second
electrode portions.
2. The apparatus of claim 1, wherein, for at least one of the first
and second electrode portions, the current electrode has an area
greater than an area of the voltage electrode.
3. The apparatus of claim 2, wherein, for the at least one of the
first and second electrode portions, the current electrode and the
voltage electrode are shaped corresponding to portions of a divided
polygon, a divided circle, or a divided oval.
4. The apparatus of claim 3, wherein, for the at least one of the
first and second electrode portions, the current electrode and the
voltage electrode are arranged such that at least one from among
the first electrode portion and the second electrode portion
comprises a polygonal shape, a circular shape, or an oval
shape.
5. The apparatus of claim 2, wherein, for the at least one of the
first and second electrode portions, one from among the current
electrode and the voltage electrode surrounds at least a portion of
the other of the current electrode and the voltage electrode.
6. The apparatus of claim 5, wherein, for the at least one of the
first and second electrode portions, the current electrode
comprises a circular shape, an oval shape, or a polygonal
shape.
7. The apparatus of claim 6, wherein, for the at least one of the
first and second electrode portions, the voltage electrode
comprises a circular ring shape, an oval ring shape, or a polygonal
ring shape and surrounds the current electrode.
8. The apparatus of claim 7, wherein, for the at least one of the
first and second electrode portions, the current electrode and the
voltage electrode respectively comprise a circular shape and a
circular ring shape and satisfy a following condition: a > - d +
2 b 2 - d 2 2 ##EQU00008## where, a is a radius of the current
electrode, b is an external radius of the voltage electrode, and d
is a distance between the current electrode and the voltage
electrode.
9. The apparatus of claim 7, wherein, for the at least one of the
first and second electrode portions, the current electrode and the
voltage electrode respectively comprise a square shape and a square
ring shape and satisfy a following condition: a > - d + 2 b 2 -
d 2 2 ##EQU00009## where, a is a length of a side of the current
electrode, b is a length of an external side of the voltage
electrode, and d is a distance between the current electrode and
the voltage electrode.
10. The apparatus of claim 7, wherein, for the at least one of the
first and second electrode portions, the current electrode and the
voltage electrode respectively comprise an oval shape and an oval
ring shape and have length ratios that are equal to k, wherein the
length ratio of the current electrode is the ratio of a long axis
of the current electrode to a short axis of the current electrode,
and the length ratio of the voltage electrode is the ratio of a
long axis of the voltage electrode to a short axis of the voltage
electrode, and the current electrode and the voltage electrode
satisfy a following condition: a > - ( k + 1 ) d + ( k + 1 ) 2 d
2 - 8 k ( d 2 - kb 2 ) 4 k ##EQU00010## where, a is a length of a
short axis of the current electrode, b is a length of a short axis
of an external oval of the voltage electrode, and d is a distance
between the current electrode and the voltage electrode.
11. The apparatus of claim 5, wherein, for the at least one of the
first and second electrode portions, the voltage electrode
comprises a circular shape, an oval shape, or a polygonal shape,
and the current electrode comprises a circular ring shape, an oval
ring shape, or a polygonal ring shape and surrounds the voltage
electrode.
12. The apparatus of claim 1, further comprising an analysis unit
configured to analyze bio information of the subject based on the
bio impedance measured by the measuring unit.
13. The apparatus of claim 12, wherein the bio information
comprises body composition or blood volume.
14. The apparatus of claim 1, wherein the apparatus is a
wrist-wearable apparatus comprising a main body and a strap.
15. The apparatus of claim 14, wherein the first electrode portion
is arranged on an inner surface of the main body or an inner
surface of the strap so as to contact a wrist of the subject, and
the second electrode portion is arranged on an outer surface of the
main body or an outer surface of the strap.
16. The apparatus of claim 1, wherein the apparatus is a portable
device comprising a front surface on which a display unit is
arranged, a rear surface opposite to the front surface, and side
portions connecting the front and rear surfaces.
17. The apparatus of claim 16, wherein one of the first and second
electrode portions is arranged on the side portions, and the other
of the first and second electrode portions is arranged on the front
surface.
18. The apparatus of claim 16, wherein one of the first and second
electrode portions is arranged on the side portions, and the other
of the first and second electrode portions is arranged on the rear
surface.
19. The apparatus of claim 16, wherein one of the first and second
electrode portions is arranged on the front surface, and the other
of the first and second electrode portions is arranged on the rear
surface.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of Korean Patent
Application No. 10-2015-0049954, filed on Apr. 8, 2015, in the
Korean Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
BACKGROUND
[0002] 1. Field
[0003] Apparatuses and methods consistent with exemplary
embodiments relate to obtaining bio information using bio
impedance.
[0004] 2. Description of the Related Art
[0005] With developments in medical science and extended life
expectancies, interest in health care and medical devices has
increased. Accordingly, various medical devices for use in
hospitals and inspection clinics, medium-sized medical devices
installed in government agencies, personal small-sized medical
devices, and personal mobile healthcare devices have been
proposed.
[0006] A body composition measurer, which is a type of health care
device, measures body composition through bioelectrical impedance
analysis (BIA). According to BIA, the impedance of a human body is
measured by applying a current to a human body, which is considered
as a combination of impedances, and measuring a voltage based on
the current. Further according to BIA, the body composition such as
moisture in the human body, an amount of protein, bones, and fat
may be analyzed based on the measured impedance.
[0007] When body composition is measured by using a bio impedance,
electrodes are directly placed in contact with a body part of a
user. Thus, contact resistance generated by the contact between the
contacts and the body part may affect measured bio impedance
values.
SUMMARY
[0008] Provided are methods and apparatuses for obtaining bio
information, which have an improved accuracy of bio impedance
measurement by taking contact resistance between electrodes and
body parts into account.
[0009] Additional aspects will be set forth in part in the
description which follows and, in part, will be apparent from the
description, or may be learned by practice of the exemplary
embodiments.
[0010] According to an aspect of an exemplary embodiment, an
apparatus for obtaining bio information, includes: a first
electrode portion including a current electrode and a voltage
electrode which are arranged to contact a first body portion of a
hand of a subject; a second electrode portion including a current
electrode and a voltage electrode which are arranged to contact a
second body portion of the other hand of the subject; and a
measuring unit configured to measure a bio impedance of the subject
by applying a current to the current electrodes of the first and
second electrode portions and detecting a voltage at the voltage
electrodes of the first and second electrode portions. Contact
resistances of the first and second body portions of the subject
contacting the current electrode and the first and second body
portions of the subject contacting the voltage electrode are
different from each other, for at least one of the first and second
electrode portions.
[0011] For at least one of the first and second electrode portions,
the current electrode may have an area greater than an area of the
voltage electrode.
[0012] For the at least one of the first and second electrode
portions, the current electrode and the voltage electrode may be
shaped corresponding to portions of a divided polygon, a divided
circle, or a divided oval.
[0013] For the at least one of the first and second electrode
portions, the current electrode and the voltage electrode may be
arranged such that the first electrode portion or the second
electrode portion is polygonal shaped, circular shaped, or oval
shaped.
[0014] For the at least one of the first and second electrode
portions, one of the current electrode and the voltage electrode
surrounds at least a portion of the other of the current electrode
and the voltage electrode.
[0015] For the at least one of the first and second electrode
portions, the current electrode may be circular, oval, or polygonal
shaped.
[0016] For the at least one of the first and second electrode
portions, the voltage electrode may be circular ring shaped, oval
ring shaped, or polygonal ring shaped and surrounds the current
electrode.
[0017] For the at least one of the first and second electrode
portions, the current electrode and the voltage electrode may be
respectively circular shaped and circular ring shaped and satisfy a
following condition:
a > - d + 2 b 2 - d 2 2 ##EQU00001##
[0018] where, a is a radius of the current electrode, b is an
external radius of the voltage electrode, and d is a distance
between the current electrode and the voltage electrode.
[0019] For the at least one of the first and second electrode
portions, the current electrode and the voltage electrode may be
respectively square shaped and square ring shaped and satisfy a
following condition:
a > - d + 2 b 2 - d 2 2 ##EQU00002##
[0020] where, a is a length of a side of the current electrode, b
is a length of an external side of the voltage electrode, and d is
a distance between the current electrode and the voltage
electrode.
[0021] For the at least one of the first and second electrode
portions, the current electrode and the voltage electrode may be
respectively oval shaped and oval ring shaped and have length
ratios that are equal to k. The length ratio of the current
electrode may be the ratio of a long axis of the current electrode
to a short axis of the current electrode, and the length ratio of
the voltage electrode may be the ratio of a long axis of the
voltage electrode to a short axis of the voltage electrode. The
current electrode and the voltage electrode satisfy a following
condition:
a > - ( k + 1 ) d + ( k + 1 ) 2 d 2 - 8 k ( d 2 - kb 2 ) 4 k
##EQU00003##
[0022] where, a is a length of a short axis of the current
electrode, b is a length of a short axis of an external oval of the
voltage electrode, and d is a distance between the current
electrode and the voltage electrode.
[0023] For the at least one of the first and second electrode
portions, the voltage electrode may be circular shaped, oval
shaped, or polygonal shaped, and the current electrode may be
circular ring shaped, oval ring shaped, or polygonal ring shaped
and may surround the voltage electrode.
[0024] The apparatus may further include an analysis unit
configured to analyze bio information of the subject based on the
bio impedance measured by the measuring unit.
[0025] The bio information may include body composition or blood
volume.
[0026] The apparatus may be a wrist-wearable apparatus including a
main body and strap.
[0027] The first electrode portion may be arranged on an inner
surface of the main body or an inner surface of the strap and may
come into contact with a wrist of the subject. The second electrode
portion may be arranged on an outer surface of the main body or an
outer surface of the strap.
[0028] The apparatus may be a portable device including a front
surface on which a display unit is arranged, a rear surface
opposite to the front surface, and side portions connecting the
front and rear surfaces.
[0029] One of the first and second electrode portions may be
arranged on the side portions, and the other of the first and
second electrode portions may be arranged on the front surface.
[0030] One of the first and second electrode portions may be
arranged on the side portions, and the other of the first and
second electrode portions may be arranged on the rear surface.
[0031] One of the first and second electrode portions may be
arranged on the front surface, and the other of the first and
second electrode portions may be arranged on the rear surface.
[0032] According to an aspect of another exemplary embodiment, an
apparatus for obtaining bio information is provided. The apparatus
includes: a first electrode portion comprising a first current
electrode and a first voltage electrode; a second electrode portion
comprising a second current electrode and a second voltage
electrode; and a measuring unit configured to measure a bio
impedance by applying a current to the current electrodes of the
first and second electrode portions and detecting a voltage at the
voltage electrodes of the first and second electrode portions. The
contact resistances between the first current electrode and the
first voltage electrode may be different from each other or the
contact resistances between the second current electrode and the
second voltage electrode may be different from each other.
[0033] The first current electrode may have an area greater than an
area of the first voltage electrode.
[0034] The first current electrode and the first voltage electrode
may comprise a shape corresponding to a divided polygon, a divided
circle, or a divided oval.
[0035] The apparatus may include an analysis unit configured to
analyze bio information based on the bio impedance measured by the
measuring unit.
[0036] The bio information may include body composition or blood
volume.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] These and/or other aspects will become apparent and more
readily appreciated from the following description of the exemplary
embodiments, taken in conjunction with the accompanying drawings in
which:
[0038] FIG. 1 illustrates a block diagram of a schematic structure
of an apparatus for obtaining bio information according to an
exemplary embodiment;
[0039] FIGS. 2A and 2B illustrate perspective views of an exterior
of an apparatus for obtaining bio information and respectively
illustrate arrangements of a first electrode portion and a second
electrode portion;
[0040] FIG. 3 illustrates a circuit diagram for electrode portions
and a measuring unit in the apparatus for obtaining bio information
of FIG. 1;
[0041] FIG. 4 illustrates a case where a body part of a subject
comes into contact with an electrode portion when a bio impedance
is measured using an apparatus for obtaining bio information
according to an exemplary embodiment;
[0042] FIGS. 5 and 6 illustrate a change of a measured bio
impedance according to contact resistance between a subject and
electrodes;
[0043] FIGS. 7A to 7F illustrate examples of shapes of a current
electrode and a voltage electrode;
[0044] FIGS. 8A to 8C illustrate other examples of shapes of a
current electrode and a voltage electrode; and
[0045] FIG. 9 illustrate an exterior of an apparatus for obtaining
bio information and a case where a body part of a subject comes
into contact with an electrode portion, according to another
exemplary embodiment.
DETAILED DESCRIPTION
[0046] The inventive concept will now be described more fully with
reference to the accompanying drawings, in which exemplary
embodiments are shown.
[0047] Like reference numerals in the drawings denote like
elements.
[0048] It will be understood that when a component, such as a
layer, a film, a region, or a plate, is referred to as being "on"
another component, the component can be directly on the other
component or intervening components may be present thereon.
[0049] While such terms as "first", "second", etc., may be used to
describe various components, such components must not be limited to
the above terms. The above terms are used only to distinguish one
component from another.
[0050] An expression used in the singular encompasses the
expression of the plural, unless it has a clearly different meaning
in the context. In the present specification, it is to be
understood that terms such as "including", "having", and
"comprising" are intended to indicate the existence of the
features, numbers, steps, actions, components, parts, or
combinations thereof disclosed in the specification, and are not
intended to preclude the possibility that one or more other
features, numbers, steps, actions, components, parts, or
combinations thereof may exist or may be added.
[0051] In the present specification, it will be understood that a
term such as a "unit" is intended to indicate a hardware component
such as a processor or a circuit, and/or a software component
implemented by a hardware component such as a processor.
[0052] FIG. 1 illustrates a block diagram of a schematic structure
of an apparatus 100 for obtaining bio information according to an
exemplary embodiment, FIGS. 2A and 2B illustrate perspective views
of an exterior of the apparatus 100 for obtaining bio information
and respectively illustrate arrangements of a first electrode
portion E1 and a second electrode portion E2, and FIG. 3
illustrates a circuit diagram for first and second electrode
portions E1 and E2 and a measuring unit 140 in the apparatus 100
for obtaining bio information of FIG. 1.
[0053] The apparatus 100 for obtaining bio information may include:
the first electrode portion E1 including a pair of a current
electrode 110 and a voltage electrode 115 which are arranged to
come into contact with a part of one hand of a subject; the second
electrode portion E2 including a pair of a current electrode 125
and a voltage electrode 120 which are arranged to come into contact
with a part of the other hand of the subject; and the measuring
unit 140 for measuring a bio impedance of the subject by applying a
current to the current electrodes 110 and 125 and detecting a
voltage across the voltage electrodes 115 and 120.
[0054] In the present exemplary embodiment, at least one of the
first electrode portion E1 and the second electrode portion E2 may
have different contact resistance when body parts of the subject
respectively come into contact with the current electrodes 110 and
125 and the voltage electrodes 115 and 120. For example, for at
least one of the first electrode portion E1 and the second
electrode portion E2, an area of the current electrode 110 may be
different from an area of the voltage electrode 115 or an area of
the current electrode 125 may be different from an area of the
voltage electrode 120.
[0055] The apparatus 100 for obtaining bio information may further
include a bio information analysis unit 150 for analyzing bio
information of the subject based on the bio impedance measured by
the measuring unit 140. The bio information may be, for example,
body composition such as body fat, moisture content, muscle
strength, an edema value, or blood volume.
[0056] The apparatus 100 for obtaining bio information may further
include, for example, a memory 160, an input unit 170 (e.g., an
input device, touch screen, touch panel, button, etc.), a display
unit 180 (e.g., a display, etc.), and a communication unit 190
(e.g., a transceiver, etc.).
[0057] The apparatus 100 for obtaining bio information may be a
wearable apparatus, for example, a wrist-wearable apparatus
including a main body MB and straps ST. In the drawings, the first
and second electrode portions E1 and E2 are placed on the straps
ST, and the measuring unit 140, the bio information analysis unit
150, the memory 160, the input unit 170, the display unit 180, and
the communication unit 190 are placed on the main body MB. However,
the inventive concept is not limited thereto.
[0058] As illustrated in FIGS. 2A and 2B, the apparatus 100 for
obtaining bio information includes the main body MB and the straps
ST. The straps ST are connected to the main body MB and may be
wearable on a wrist of the subject. The first current electrode 110
and the first voltage electrode 115 are arranged on an inner
surface STb of any one of the straps ST, and the second current
electrode 120 and the second voltage electrode 125 are arranged on
an outer surface STa of any one of the straps ST.
[0059] The first current electrode 110 and the first voltage
electrode 115 are electrodes contacting a wrist of the subject when
a user, that is, the subject whose body composition is to be
measured, wears the apparatus 100 for obtaining bio information.
The first current electrode 110 and the first voltage electrode 115
may be arranged on locations where the first current electrode 110
and the first voltage electrode 115 may contact the wrist of the
subject, but the locations are not limited to the inner surface STb
of the straps ST. For example, the first current electrode 110 and
the first voltage electrode 115 may be arranged on an inner surface
of the main body MB.
[0060] The second current electrode 120 and the second voltage
electrode 125 are electrodes contacting a part of the other wrist
on which the apparatus 100 for obtaining bio information is not
placed. The second current electrode 120 and the second voltage
electrode 125 may be arranged to be exposed to the outside of the
apparatus 100 for obtaining bio information such that the second
current electrode 120 and the second voltage electrode 125 may
contact a part of the other wrist. However, locations of the second
current electrode 120 and the second voltage electrode 125 are not
limited to the outer surface STa of the straps ST. For example, the
second current electrode 120 and the second voltage electrode 125
may be arranged on an outer surface of the main body MB.
[0061] The first current electrode 110 and the first voltage
electrode 115 respectively face the second current electrode 120
and the second voltage electrode 125, but the first current
electrode 110 and the first voltage electrode 115 may not
accurately face the second current electrode 120 and the second
voltage electrode 125. The first current electrode 110, the first
voltage electrode 115, the second current electrode 120, and the
second voltage electrode 125 are arranged in a direction
perpendicular to a lengthwise direction of the straps ST, but the
inventive concept is not limited thereto. The first current
electrode 110, the first voltage electrode 115, the second current
electrode 120, and the second voltage electrode 125 may be arranged
in another direction, for example, a direction parallel to the
lengthwise direction of the straps ST, or other directions. In the
first electrode portion E1 and the second electrode portion E2,
areas of the current electrodes 110 and 125 are greater than areas
of the voltage electrodes 115 and 120, but the present exemplary
embodiment is not limited thereto. In any one of the first
electrode portion E1 and the second electrode portion E2, for
example, only in the second electrode portion E2, an area of the
current electrode 125 may be greater than an area of the voltage
electrode 120. Shapes of the current electrodes 110 and 125 and the
voltage electrodes 115 and 120 are not limited thereto.
[0062] Referring back to FIG. 1, other components of the apparatus
100 for obtaining bio information will be described.
[0063] The bio information analysis unit 150 may analyze bio
information of the subject by using the bio impedance measured by
the measuring unit 140. For example, body composition such as
characteristics of skin (for example, moisture content), muscle
strength, and an edema value, or blood volume may be analyzed based
on the bio impedance. The bio impedance, the user, that is, the
body information of the subject may be used to analyze the bio
information. The bio information may be an age, height, weight,
etc. of the user and may be received from the current unit 170.
[0064] Various operations used by the bio information analysis unit
150 may be stored as programs in the memory 160 and executed by a
processor (not shown). The processor may be hardware for
controlling overall functions and operations of the apparatus 100
for obtaining bio information, and the bio information may be
analyzed by the bio information analysis unit 150 when the programs
stored in the memory 160 are executed. In addition, the processor
may control the measuring unit 140 to measure a bio impedance and
may process an analysis result as an image signal for displaying an
analysis result on the display unit 180.
[0065] The memory 160 may store programs for operations of the
apparatus 100 for obtaining bio information, data used for the
programs, etc. therein. The memory 160 is a conventional storage
medium and may include, for example, a hard disk drive (HDD), read
only memory (ROM), random access memory (RAM), flash memory, and a
memory card.
[0066] The memory 160 may store programs for operations to be
performed by the bio information analysis unit 150 therein.
Additional data such as an age, weight, gender, etc. of the subject
may be stored in the memory 160.
[0067] The input unit 170 and the display unit 180 form an
interface between the apparatus 100 for obtaining bio information
and the subject or a user.
[0068] An input for manipulating the apparatus 100 for obtaining
bio information may be received via the input unit 170, and a
result output from the bio information analysis unit 150 may be
displayed on the display unit 180.
[0069] The input unit 170 may include a button, a keypad, a switch,
a dial, or a touch interface used by the subject to directly
manipulate the apparatus 100 for obtaining bio information.
[0070] The display unit 180 that is a display panel for outputting
an analysis result may include a liquid crystal display (LCD)
panel, an organic light-emitting display (OLED) panel, or the like,
and may display information about an analysis result of the body
composition as an image or text. The display unit 180 may be a
touch screen capable of receiving an input or displaying an
output.
[0071] Moreover, the display unit 180 may include an input/output
(I/O) port for connecting human interface devices (HIDs) to one
another and an I/O port for inputting/outputting an image.
[0072] The communication unit 190 may transmit the analysis result
to an external device in a wired or wireless manner. The external
device may be, for example, a medical apparatus using analyzed bio
information, a printer for printing an analysis result, or a
display apparatus for displaying an analysis result. Alternatively,
the external device may be a smart phone, a mobile phone, a
personal digital assistant (PDA), a laptop computer, a PC, another
mobile device or a non-mobile computing device, but is not limited
thereto.
[0073] The communication unit 190 may be connected to the eternal
device in a wired or wireless manner. For example, the
communication unit 190 may communicate with the eternal device by a
Bluetooth communication method, a Bluetooth low energy (BLE)
communication method, a near field communication (NFC)
communication method, a wireless LAN (WLAN) communication method, a
Zigbee communication method, an infrared data association (IrDA)
communication method, a Wi-Fi direct (WFD) communication method, a
ultra wideband (UWB) communication method, an Ant+ communication
method, and a Wi-Fi communication method, but the communication
method is not limited thereto.
[0074] As illustrated in FIGS. 2A and 2B, in the apparatus 100 for
obtaining bio information that is a small electronic device, small
electrodes are used to measure a bio impedance. However, as sizes
of the electrodes decrease, contact resistance generated by contact
of the electrodes with a body part may increase. The contact
resistance affects the measurement of the bio impedance. A large
electrode area may be advantageous for decreasing the contact
resistance, but when the apparatus 100 for obtaining bio
information is a wearable device, there is a limit on increasing
the electrode area.
[0075] In the apparatus 100 for obtaining bio information, in order
to accurately measure the bio impedance, sizes of the current
electrodes 110 and 125 may be different from those of the voltage
electrodes 115 and 120 by considering the contact resistance, and
detailed descriptions thereof are as follows.
[0076] A circuit configuration via which the measuring unit 140
measures the bio impedance will be briefly described with reference
to FIG. 3.
[0077] The measuring unit 140 measures the bio impedance by a bio
impedance analyzer (BIA) method. As illustrated, the bio impedance
of the subject may be measured by a 4-point measuring method. That
is, the measuring unit 140 may measure an impedance by applying a
constant current Im via two of four electrodes, measuring a voltage
via the other two of four electrodes, and calculating a ratio of
the voltage to the applied constant current.
[0078] Zm indicates a bio impedance, and Rc indicates contact
resistance, that is, resistance generated due to contact of the
current and voltage electrodes 110, 115, 120 and 125 with a body
part of the subject. Zi indicates an impedance of analog front end
(AFE).
[0079] The measuring unit 140 includes a voltmeter 141, a current
source 142, and an analog to digital converter (ADC) 143.
[0080] The current source 142 applies a current to a human body via
the current electrodes 110 and 125. The current source 142 may
apply a constant current to the human body.
[0081] The voltmeter 141 measures a voltage via the voltage
electrodes 115 and 120. The voltmeter 141 outputs the measured
voltage to the ADC 143.
[0082] The ADC 143 converts a voltage that is input as an analog
signal to a digital signal. Since magnitude of the current is
fixed, magnitude of the measured voltage is proportional to a size
of the bio impedance Zm. A voltage Vi measured by the measuring
unit is proportional to an impedance Z.sub.4P, and the impedance
Z.sub.4P may be equal to the voltage Vi divided by current. The
impedance Z.sub.4P may be described as follows.
Z 4 P = f 1 ( Z m , R c , Z i ) = Z m 1 1 + Z m + 2 R c Z i [
Equation 1 ] ##EQU00004##
[0083] Referring to the Equation 1, Z.sub.4P is determined by Zm,
Rc, and Zi. Zi is the impedance of the AFE and is determined
according to characteristics of the AFE. Z.sub.4P is an impedance
measured by the voltmeter 141. Zm is a bio impedance to be
measured, and Rc is the contact resistance.
[0084] Referring to the Equation 1, if Zi is infinite, Z.sub.4P is
equal to Zm. However, Zi is actually finite, Z.sub.4P is smaller
than Zm as the contact resistance increases. In other words, as the
contact resistance increases, the measured bio impedance may be
smaller than an actual bio impedance.
[0085] When contact resistance of a current electrode increases, a
time taken to stabilize a measurement value, and thus the
measurement value may have an error.
[0086] As described above, when the bio impedance is measured, a
constant current of a sine wave is applied to the current
electrodes 110 and 125, and a voltage signal generated based on the
bio impedance is measured by the voltage electrodes 115 and 120 and
may thereby be used to calculate the bio impedance Zm. In this
case, resistance driven by a constant current is an impedance
element which includes the contact resistance Rc and the bio
impedance Zm, and voltages applied to both ends of the current
source 142 are as follows.
V=I.sub.m.times.(2R.sub.c+Z.sub.m) [Equation 2]
[0087] Referring to Equation 2, when the contact resistance Rc
increases, voltages applied to the both ends of the current source
142 having a constant current increase and then may exceed a
dynamic range. Thus, an output current value may have an error, and
an output wave form may be distorted. Voltage signals may not be
stabilized, since the current source 142 abnormally operates.
[0088] FIG. 4 illustrates a case where a body part of a subject
comes into contact with an electrode portion when a bio impedance
is measured using the apparatus 100 for obtaining bio information
according to an exemplary embodiment, and FIGS. 5 and 6 illustrate
a change of the measured bio impedance according to contact
resistance between a subject and electrodes.
[0089] Referring to FIG. 4, the subject wears the apparatus 100 for
obtaining bio information on a wrist and may touch the current
electrode 125 and the voltage electrode 120 with fingers of the
other hand. In this case, it is advantageous to fully touch the
current electrode 125 and the voltage electrode 120 with the finger
f1 in order to decrease the contact resistance. However, it may be
uncomfortable to fully touch the current electrode 125 and the
voltage electrode 120 according to shapes, areas, arrangements,
etc. thereof. Therefore, the current electrode 125 and the voltage
electrode 120 may be shaped such that the current electrode 125 and
the voltage electrode 120 may easily contact the subject, which
greatly affects a measurement result. For example, an area of the
current electrode 125 may be greater than an area of the voltage
electrode 120.
[0090] A result of testing the above design is as follows.
[0091] FIG. 5 is a graph showing a result of measuring an impedance
while contact resistance of a current electrode changes. A case 1
is a state in which a finger is fully placed in contact with the
current electrode, and a case 2 is a state in which half of a
finger is placed in contact with the current electrode. That is, in
the case 2, contact resistance of the current electrode is two
times as great as contact resistance in the case 1. A measurement
value of an impedance in the case 1 is smaller than a measurement
value of an impedance in the case 2.
[0092] FIG. 6 is a graph showing a result of measuring an impedance
while contact resistance of a voltage electrode changes. A case 3
is a state in which a finger is fully placed in contact with the
voltage electrode, and a case 4 is a state in which half of a
finger is placed in contact with the voltage electrode. That is, in
the case 4, contact resistance of the voltage electrode is two
times as great as contact resistance in the case 3. A measurement
value of an impedance in the case 3 is smaller than a measurement
value of an impedance in the case 4.
[0093] Referring to the above graphs, errors of the measured
impedance according to an increase of the contact resistance may be
sensitive to the contact resistance of the current electrode rather
than the contact resistance of the voltage electrode.
[0094] According to analysis results, electrodes are designed in
such a way that the contact resistance of the current electrode is
smaller than the contact resistance of the voltage electrode.
[0095] Hereinafter, exemplary shapes of a current electrode and a
voltage electrode will be described.
[0096] FIGS. 7A to 7F illustrate examples of shapes of a current
electrode ELC and a voltage electrode ELV.
[0097] As illustrated in FIGS. 7A to 7F, in the first electrode
portion E1 or the second electrode portion E2, an area of a current
electrode ELC is set to be greater than an area of a voltage
electrode ELV. The areas of the current electrode ELC and the
voltage electrode ELV may be determined as follows. A sum of the
areas of the current electrode ELC and the voltage electrode ELV is
set to be the greatest under predetermined conditions. In this
case, areas or locations where the current electrode ELC and the
voltage electrode ELV are arranged, or body parts to be placed in
contact with the current electrode ELC and the voltage electrode
ELV are considered. For example, when a finger contacts the current
electrode ELC and the voltage electrode ELV, if the areas of the
current electrode ELC and the voltage electrode ELV are excessively
greater than areas where the fingers may contact, a decrease of the
contact resistance may be slight. After an entire area is
determined, areas of the electrodes, that is, the areas of the
current electrode ELC and the voltage electrode ELV, are assigned,
and in this case, the area of the current electrode ELC is greater
than that of the voltage electrode ELV. Thus, a distribution of the
contact resistance may be optimized to decrease errors in measuring
the bio impedance.
[0098] As illustrated in FIGS. 7A to 7F, the current electrode ELC
and the voltage electrode ELV may have shapes corresponding to
portions of a divided polygon, a divided circle, or a divided oval.
For example, shapes and locations of the current electrode ELC and
the voltage electrode ELV may be determined such that exteriors of
the first electrode portion E1 and the second electrode portion E2
may be polygonal shaped, circular shaped, or oval shaped.
[0099] As described above, the areas of the current electrode ELC
and the voltage electrode ELV may be determined by taking the
entire area and the distribution of contact resistance into
account. Additionally, convenient contact with body parts may also
be considered.
[0100] As illustrated in FIGS. 7B, 7C, and 7F, the current
electrode ELC and the voltage electrode ELV may have a shape in
which any one of the current electrode ELC and the voltage
electrode ELV surrounds at least a portion of the other one of the
current electrode ELC and the voltage electrode ELV.
[0101] FIGS. 8A to 8C illustrate other examples of shapes of the
current electrode ELC and the voltage electrode ELV.
[0102] A shape of the first electrode portion E1 or the second
electrode portion E2 is determined in such a way that, for example,
the subject may easily touch the electrodes with fingers by taking
a position of the subject into account.
[0103] The current electrode ELC and the voltage electrode ELV may
have a shape in which any one of the current electrode ELC and the
voltage electrode ELV surrounds at least a portion of the other one
of the current electrode ELC and the voltage electrode ELV. As
illustrated in FIGS. 8A to 8C, the voltage electrode ELV may be
arranged to surround an entire portion of the current electrode
ELC.
[0104] The current electrode ELC may be circular shaped, oval
shaped, or polygonal shaped. The voltage electrode ELV may be
circular ring shaped, oval ring shaped, or polygonal ring shaped
and surrounds the current electrode ELC. FIG. 8B illustrates a
square ring shape, but the shape of the current electrode ELC and
the voltage electrode ELV is not limited thereto.
[0105] As illustrated in FIG. 8A, the current electrode ELC and the
voltage electrode ELV may respectively be circular shaped and
circular ring shaped, and in this case, the following condition may
be satisfied such that an area of the current electrode ELC may be
greater than an area of the voltage electrode ELV.
a > - d + 2 b 2 - d 2 2 [ Equation 3 ] ##EQU00005##
[0106] where, a is a radius of the current electrode ELC, b is an
external radius of the voltage electrode ELV, and d is a distance
between the current electrode ELC and the voltage electrode
ELV.
[0107] As illustrated in FIG. 8B, the current electrode ELC and the
voltage electrode ELV may respectively have square and square ring
shapes, and in this case, the following condition may be satisfied
such that the area of the current electrode ELC may be greater than
the area of the voltage electrode ELV.
a > - d + 2 b 2 - d 2 2 [ Equation 4 ] ##EQU00006##
[0108] where, a is a length of a side of the current electrode ELC,
b is a length of an external side of the voltage electrode ELV, and
d is a distance between the current electrode ELC and the voltage
electrode ELV.
[0109] As illustrated in FIG. 8C, the current electrode ELC and the
voltage electrode ELV may respectively be oval or oval ring shaped.
The oval shapes of the current electrode ELC and the voltage
electrode ELV are similar, as respective length ratios of the
current electrode ELC and the voltage electrode ELV are both equal
to k. The length ratio of the current electrode ELC is the ratio of
a long axis of the current electrode ELC to a short axis of the
current electrode ELC, and the length ratio of the voltage
electrode ELV is the ratio of a long axis of the voltage electrode
ELV to a short axis of the voltage electrode ELV. The following
condition may be satisfied such that the area of the current
electrode ELC may be greater than the area of the voltage electrode
ELV.
a > - ( k + 1 ) d + ( k + 1 ) 2 d 2 - 8 k ( d 2 - kb 2 ) 4 k [
Equation 5 ] ##EQU00007##
[0110] where, a is a length of a short axis of the current
electrode ELC, b is a length of a short axis of an external oval of
the voltage electrode ELV, and d is a distance between the current
electrode ELC and the voltage electrode ELV.
[0111] FIGS. 8A to 8C illustrate that the voltage electrode ELV
surrounds the current electrode ELC, but this is merely an example.
The current electrode ELC may surround the voltage electrode ELV.
In this case, direction of inequality signs of Equations 3 to 5 may
be reversed such that the area of the current electrode ELC may be
greater than the area of the voltage electrode ELV.
[0112] FIG. 9 illustrate an exterior of an apparatus 200 for
obtaining bio information and a case where a body part of a subject
comes into contact with an electrode portion, according to another
exemplary embodiment.
[0113] As shown in FIG. 9, the apparatus 200 may be of a
portable-device type. The apparatus 200 for obtaining bio
information may include a front surface on which a display unit is
disposed, a rear surface opposite to the front surface, and side
portions connecting the front surface and the rear surface. A first
electrode portion E1 may be arranged on the side portions. A
current electrode and a voltage electrode of the first electrode
portion E1 may be arranged on side portions which face each other
from among four side portions. When the subject holds the apparatus
200 for obtaining bio information with one hand, two fingers of the
hand may come into contact with the current electrode and the
voltage electrode of the first electrode portion E1. In the
drawing, the current electrode and the voltage electrode of the
first electrode portion E1 are respectively arranged on the side
portions of the apparatus 200 for obtaining bio information which
face each other, but may be arranged on the same side portion. A
second electrode portion E2 may be arranged on the front surface. A
finger of the other hand which does not hold the apparatus 200 for
obtaining bio information may be in contact with the second
electrode portion E2.
[0114] FIG. 9 illustrates that the first electrode portion E1 is
arranged on the side portions and the second electrode portion E2
is arranged on the front surface, but this is merely an example.
The first electrode portion E1 may be arranged on the front surface
and the second electrode portion E2 may be arranged on the rear
surface.
[0115] Alternatively, the first electrode portion E1 and the second
electrode portion E2 may be arranged on the front surface and the
rear surface. That is, any one of the first electrode portion E1
and the second electrode portion E2 may be arranged on the front
surface, and the other of the first electrode portion E1 and the
second electrode portion E2 may be arranged on the rear surface. In
this case, a palm of the hand on which the apparatus 200 for
obtaining bio information is placed may be in contact with the
first electrode portion E1 (or the second electrode portion E2),
and a finger of the other hand on which the apparatus 200 for
obtaining bio information is not placed may be in contact with the
second electrode portion E2 (or the first electrode portion
E1).
[0116] Alternatively, the first electrode portion E1 and the second
electrode portion E2 may be arranged on the side portions and the
rear surface. That is, any one of the first electrode portion E1
and the second electrode portion E2 may be arranged on the side
portions, and the other of the first electrode portion E1 and the
second electrode portion E2 may be arranged on the rear
surface.
[0117] In at least one of the first electrode portion E1 and the
second electrode portion E2, an area of the current electrode may
be greater than an area of the voltage electrode. Besides the shape
in FIG. 9, any one of the shapes illustrated in FIGS. 7A to 7F or
FIGS. 8A to 8C, a combination thereof, or a modification of the
shapes may be applied.
[0118] Examples, in which contact resistance between electrodes and
body parts are differently set to decrease measurement errors when
a bio impedance that may be used to analyze bio information is
measured, have been described. An example in which an area of a
current electrode is greater than an area of a voltage electrode
has been mainly described, but the inventive concept is not limited
thereto. In addition, various methods by which contact resistance
of the current electrode is smaller than contact resistance of the
voltage electrode may be used.
[0119] The apparatus for obtaining bio information sets electrode
shapes by taking contact resistance between electrodes and body
parts when a bio impedance is measured into account, and thus
measurement accuracy of the bio impedance is improved.
[0120] Therefore, analysis accuracy of bio information using the
measured bio impedance is improved.
[0121] It should be understood that exemplary embodiments described
herein should be considered in a descriptive sense only and not for
purposes of limitation. Descriptions of features or aspects within
each exemplary embodiment should typically be considered as
available for other similar features or aspects in other exemplary
embodiments.
[0122] While one or more exemplary embodiments have been described
with reference to the figures, it will be understood by those of
ordinary skill in the art that various changes in form and details
may be made therein without departing from the spirit and scope as
defined by the following claims.
* * * * *